It is well known that elemental sulfur in hydrocarbon streams, such as petroleum streams, is corrosive and damaging to metal equipment, particularly copper and copper alloys. Elemental sulfur and sulfur compounds may be present in varying concentrations in refined petroleum streams. Additional contamination will typically take place as a consequence of transporting the refined stream through pipelines that contain sulfur contaminants remaining in the pipeline from the transportation of sour hydrocarbon streams, such as petroleum crudes. The sulfur also has a particularly corrosive effect on equipment, such as brass valves, gauges and in-tank fuel pump copper commutators.
Various techniques have been reported for removing elemental sulfur from petroleum streams. For example, U.S. Pat. No. 4,149,966 discloses a method for removing elemental sulfur from refined hydrocarbon fuels by adding an organo-mercaptan compound plus a copper compound capable of forming a soluble complex with the mercaptan and sulfur. The fuel is contacted with an adsorbent material to remove the resulting copper complex and substantially all the elemental sulfur.
U.S. Pat. No. 4,011,882 discloses a method for reducing sulfur contamination of refined hydrocarbon fluids transported in a pipeline for the transportation of sweet and sour hydrocarbon fluids by washing the pipeline with a solution containing a mixture of light and heavy amines, a corrosion inhibitor, a surfactant and an alkanol containing from 1 to 6 carbon atoms.
U.S. Pat. No. 5,618,408 teaches a method for reducing the amount of sulfur and other sulfur contaminants picked-up by refined hydrocarbon products, such as gasoline and distillate fuels, that are pipelined in a pipeline used to transport heavier sour hydrocarbon streams. The method involves controlling the level of dissolved oxygen in the refined hydrocarbon stream that is to be pipelined.
The removal of elemental sulfur from pipelined fuels is also addressed in U.S. Pat. No. 5,250,181 which teaches the use of an aqueous solution containing a caustic, an aliphatic mercaptan, and optionally a sulfide to produce an aqueous layer containing metal polysulfides and a clear fluid layer having a reduced elemental sulfur level. U.S. Pat. No. 5,199,978 teaches the use of an inorganic caustic material, an alkyl alcohol, and an organo mercaptan, or sulfide compound, capable of reacting with sulfur to form a fluid-insoluble polysulfide salt reaction product at ambient temperatures. It also teaches very long residence times of about 30 seconds to a few hours. The present invention only requires a residence time of a few seconds or less.
Also, U.S. Pat. No. 5,674,378 teaches a process for removing elemental sulfur from various hydrocarbon process streams by use of a treatment solution comprised of water or immiscible alcohol, caustic sulfide or hydrosulfide under dynamic mixing conditions.
While such methods have met with varying degrees of success, there still exists a need in the art for a method capable of reducing the amount of elemental sulfur in hydrocarbon streams, especially those that are transported through a pipeline.